Question

What are the advantages and disadvantages to having our brains as specialized and lateralized as they are? Considering the various aspects of brain development.

Answer 1

What are the advantages and disadvantages to having our brains as specialized and lateralized as they are? Considering the various aspects of brain development.

Brain Lateralization
Brain lateralization is common among vertebrates. However, despite its implications for higher-order cognitive functions, almost no empirical evidence has been provided to show that it may confer any advantage to the functioning of the brain. Cerebral Lateralization is associated with an enhanced ability to perform two tasks simultaneously finding food and being vigilant for predators. This finding suggests that cerebral lateralization enhances brain efficiency in cognitive tasks that demand the simultaneous but different use of both hemispheres

The above table Helps to Understand the Advantages and Disadvantages

Disadvantages of brain Laterization:

On purely theoretical grounds, there appear to be obvious disadvantages to possessing a perceptual system that is asymmetrical to any substantial degree. This point has been stressed by Corballis (1998). The physical world is indifferent to left and right, and any lateralized deficit might leave an animal vulnerable to attack on one side or unable to attack prey or competitors appearing on one side

Note that, because perceptual asymmetries have usually been revealed in humans under very artificial conditions (i.e., tachistoscopic viewing or dichotic listening), it was probably not unreasonable to maintain that asymmetries cannot be apparent in everyday behavior. Now we are learning from ethologists that such asymmetries in behavior are not rare but are in fact quite ubiquitous in animals (and it now seems likely that they may be ubiquitous in humans too; see e.g., Güntürkün [2003a] and Bracha et al. [1987] for turning biases in humans).

The existence of population-level, lateral biases in behavior of the types described above is puzzling from a biological point of view, because it provides the organisms expressing such asymmetries with obvious disadvantages. Consider the case of toads. As we have mentioned, these animals are more likely to react when a predator appears on their left side than on their right side, but predators, in principle, can appear on either side at random. Hence, lateralization would obviously be disadvantageous to the toads. On the other hand, a prey species might avoid predation if it can predict the strategy of its predator (e.g., a right-side bias for the predator to strike at its prey; see Hori 1993), and under this condition population-level lateralized behavior of a predator would be advantageous for the prey though not for the predator itself. In other words, a dynamic relationship might be established between lateralized behavior in interacting asymmetric organisms. To anticipate the key argument of this paper, we shall argue that the population structure of lateralization (i.e., the alignment of the direction of lateral biases in most individuals in a population) may have evolved as an “evolutionarily stable strategy” (Maynard-Smith 1982) to coordinate behavior among asymmetric individuals. Before considering our hypothesis, however, let us consider some alternative views.

A possible explanation for the maintenance of population-level lateral biases would be to argue that the advantages associated with possession of an asymmetric brain counteract ecological disadvantages associated with lateral biases in overt behavior. But what sort of advantages might cerebral lateralization offer?

Possible advantages of cerebral lateralization

A crucial advantage that lateralization may offer is to increase neural capacity, because specializing one hemisphere for a particular function leaves the other hemisphere free to perform other (additional) functions (Levy 1977). This would allow brain evolution to avoid useless duplication of functions in the two hemispheres, thus saving on neural circuitry. Recent evidence in support of this hypothesis has come from research on an invertebrate species, the fruitfly: Pascual et al. (2004) have discovered that, compared to fruitflies with symmetrical brain structure, fruitflies with asymmetrical brain structure have superior ability to form long-term memory. More generally, by enabling separate and parallel processing to take place in the two hemispheres, lateralization could be one way of increasing the brain’s capacity to carry out simultaneous processing. We have argued elsewhere, for instance, that incompatibility of function, other than competition for space, may have contributed to the evolution of cognitive lateralization (Vallortigara et al. 1999). Some recent evidence supports this hypothesis. For example, Rogers (2000) tested chicks on a dual task, one involving the left hemisphere in control of pecking responses and the other involving the right hemisphere in monitoring overhead to detect a model predator. Chicks exposed to light before hatching were compared to those incubated in the dark, as the light exposure aligns and strengthens visual lateralization on a number of tasks (Rogers 1990; 1997; also discussed in sect. The strongly lateralized (light-exposed) chicks detected the model predator sooner than did the weakly lateralized (dark-incubated) ones, at least with the left eye (i.e., when the right hemisphere was attending to the stimulus). This suggests that lateralization of these two types of processing into the separate hemispheres enhances performance, and this result has been confirmed recently by scoring not only the response to the model predator but also the chick’s ability to learn to peck at grain versus pebbles (Rogers et al. 2004). Strongly lateralized chicks learned to avoid pecking at pebbles far better than did weakly lateralized chicks and they were also more responsive to the model predator. In fact, the weakly lateralized chicks frequently failed to detect the model predator as it passed overhead and they were less and less able to discriminate grain from pebbles as the task progressed; they were unable to attend to the two separate tasks simultaneously. As a control, we tested the weakly lateralized chicks on the pebblegrain task without presenting the model predator and found that they had less difficulty in learning to discriminate grain from pebbles (also found in another study by Rogers 1997). Hence, the weakly lateralized chicks had their greatest difficulties when they were tested in the dual-task paradigm

A second advantage of lateralization is that dominance by one hemisphere (or in general by one side of the brain) is likely to be a convenient way of preventing the simultaneous initiation of incompatible responses in organisms with laterally placed eyes (Andrew 1991; Vallortigara 2000). This problem is particularly acute in vertebrates that lack a mobile neck, as in most species of fish. As we have seen above, the left and right hemifields of fish and birds exhibit a large degree of independence, and it is not infrequent that, because of independent scanning by the two eyes, the left and right halves of the world seen by these animals are completely different. In fact, the two eyes can scan independently in a number of species distributed throughout the vertebrate classes of birds, reptiles and fish (Andrew 1991; Wallman & Pettigrew 1985). Clearly, in such circumstances, dominance by one side of the brain – for example, through inhibitory connections with the other side – would be the only way to guarantee a proper course of action for the “unitary” organism. Ingle (1973) found that frogs could select between prey objects seen in the lateral fields of both eyes, and suggested that interhemispheric communication must play a crucial role in reducing potential competition of response emission. It is also possible that this occurs with a consistent lateral bias of one hemisphere over the other .

The problem with all these views, however, is that, although the hypothesis of a computational advantage may explain individual lateralization, it does not in itself explain the alignment in the direction of lateralization at the population level. In fact, individual brain efficiency is unrelated to how other individuals are lateralized. Why, therefore, do most animals (usually 65–90%) possess a left eye (or hemi field) better suited than the right eye for vigilance against predation? Would it not be simpler for brain lateralization to be present in individuals without any specification of its direction (i.e., with a 50:50 distribution of the left and right forms in the population)

Brain Specialization theory

One of findings came from an experiment in which we used adjectives to change the meaning of the same noun. For example, the word "book" in "green book" refers to something concrete – that is, something for which it is easy to create a mental image. However, given "interesting book" people now usually think about the content of the book rather than its physical form, so the same word has become more "abstract" in meaning.

A lot of research shows that concrete and abstract words are processed differently in the brain. We wanted to see if those differences could be found for exactly the same word depending on what it was referring to, and whether the two hemispheres were similarly affected by concreteness. We found in this experiment, as we had previously in many others, that the left hemisphere is very sensitive to the predictability of word combinations. Fewer nouns can go with "green" than with "interesting," and brain activity elicited in response to "book" reflected this when the words were presented initially to the left hemisphere.

However, to our surprise, it was the right hemisphere that elicited imagery-related brain activity to "green book" compared to "interesting book." Thus, although the left hemisphere is clearly important for language processing, the right hemisphere may play a special role in creating the rich sensory experience that often accompanies language comprehension ... and that makes reading such a pleasure.

Another popular idea is that some people are more "left brained" and others more "right brained." Is there any evidence for individual differences in the extent to which people rely on one hemisphere versus another? More generally, what kinds of individual differences do you see in hemispheric specialization?

There are certainly individual differences in hemispheric specialization across people, but they are very difficult to reliably determine. Where this matters most is in medical contexts: when people are going to have brain surgery (e.g., for epilepsy or tumor resection), physicians would like to make sure that in removing certain brain tissue they are not going to disrupt critical functions like language.

As I mentioned already, most of the time the left hemisphere is more important for speaking, for example, but that isn't true in absolutely everyone. In order to determine if a person's left or right hemisphere is more important for their language production, physicians use things like the WADA test, in which a barbiturate is injected into one hemisphere to temporarily shut it down, allowing the physician to see what each hemisphere can do on its own. This is obviously a very invasive test (and not perfect at that). If it were possible to instead figure out whether someone relied more on their left or right hemisphere by having them look at a spinning figure or answer a few questions, that would obviously be preferable ... but it doesn't work.

There are, of course, differences in how people learn and think, what they like, and what they are like (although, since everyone's brain is different, I think the similarities are actually more surprising than the differences). Some of these differences may arise because of individual differences in how the hemispheres are organized or which hemisphere tends to be used in particular circumstances. Given that the hemispheres do operate somewhat independently, the question of how their independent processing is eventually combined and/or which hemisphere gets to "take control" of processing for a particular task is one that we are only beginning to understand. (In some cases, split-brain patients' hands – one controlled by each hemisphere – literally fought for control of a particular task; it is intriguing to imagine that kind of struggle routinely taking place internally for everyone else!)

However, it seems safe to say that for the most part we all use both sides of our brains almost all the time. We do know a few factors that influence how functions are lateralized and how much they are lateralized. For example, having a "reversed" laterality (with, for example, control of speech in the right rather than the left hemisphere) is more likely for left-handed than right-handed people (although it is important not to overgeneralize from this: the vast majority of left-handed people have the typical lateralization pattern). Moreover, differences have been seen among right-handed people depending on whether or not they have left-handed biological relatives; this is something my lab is beginning to explore. Again, small biological shifts, caused in part by (complex) genetic differences, can lead to different functional patterns, including whether a function tends to be very lateralized or accomplished by both hemispheres.

I will end with one last fact about hemispheric differences that many people may not be aware of, and that is that lateralization of function changes with normal aging. The kinds of lateralized patterns of brain activity I mentioned earlier when talking about brain mapping studies are more common in young adults. Across many types of tasks and many brain areas, these lateralized patterns tend to switch to bilateral patterns in healthy older adults.

Is this because older adults have better learned how to be both logical AND creative? Maybe :-). It is actually difficult to know when this kind of a shift is helpful – for example, bringing extra processing resources to bear on a task to compensate for age-related declines in function – versus when it might be a sign that the brain is simply less good at maintaining a healthy division of labor. Understanding hemispheric specialization is thus also important for discovering ways to help us all maintain better cognitive functioning with age.

Advantages

1. Right-brained people are creative.

Right-brained people tend to be more skilled in the arts. We are normally seen taking classes in music, art and writing, and actually enjoy them. We are visual people, preferring to learn with pictures and charts, and love to problem-solve in our own way.

2. Right-brained people are more impulsive.

Whenever we are put into situations, we tend to think less. We make quick decisions, which can most likely hurt us. If you are making a decision on spending, you may make the wrong choice because you wanted the item, but you didn’t actually need it. On major life choices, you may choose a path that you think is right, but then you may later realize that the other choice was the better one.

3. Right-brained people are hands-on learners.

We like to learn by having people give us step-by-steps of how to do something. In class, we want examples, visuals and extra guidance to help us learn. We like connecting to real-life examples and if we don't have that, it's hard for us to learn.

4. Right-brained people are communicators.

We are the best at communicating. If we are meeting someone new, they can know our whole life story by the time we’re finished having a conversation. We can remember details well, and use our creative skills as we talk to gain that social relationship with a person.

5. Right-brained people are imaginative.

Our imagination can run wild at different points in time. Right-brainers are daydreamers, and love to visualize different scenarios in our minds. We love to make up and tell stories with as much detail as possible.

6. Right-brained people are more emotional.

Right-brainers are more talkative. Naturally, we start conversations and like to tell people exactly what we’re thinking. If you ask us how our day was, we will tell you in full detail about what we liked and did not like about it. We constantly overthink and overreact, as we often pay too much attention to the little things

Disadvantages of Specialized Brain/right brain

1. Learning might be difficult

If you get a professor in college who lectures too much, right-brainers may not be able to learn well. Just by speaking to us, we aren’t able to retain information as quickly as others are able to. We need examples and hands-on learning or else we will get lost during classes.

2. Working by yourself can get hard.

If you have to work on a project by yourself with no guidance or help, you may be in trouble. Right-brainers need the extra assistance to push through work. By working in groups, this allows our imagination to flow because of the ideas you may get from others. If we just work alone, we might not be able to get our ideas straight.

If you have to work on a project by yourself with no guidance or help, you may be in trouble. Right-brainers need the extra assistance to push through work. By working in groups, this allows our imagination to flow because of the ideas you may get from others. If we just work alone, we might not be able to get our ideas straight.

3. Certain subjects are hard for you.

With the education system, you are required to take a full range of classes that you might not want to take. For example, math and sciences may get boring for right-brainers, and might be too difficult to understand. The analysis and logic involved in these subjects may confuse our minds. If you give us an artistic subject, we will be able to understand the class fully.

4. Organization is not our strongest suit.

Organization is hard for imaginative people. When writing essays, we gather our thoughts only as we put words onto paper. We cannot lay out our topics and write from there. We are go-with-the-flow type of people.

Organization is hard for imaginative people. When writing essays, we gather our thoughts only as we put words onto paper. We cannot lay out our topics and write from there. We are go-with-the-flow type of people.

5. We lack time-management skills.

Time-management is not one of our strengths. We have the tendency to put things off until the last minute, which causes us to rush and it reflects in our work. It makes us feel stressed out because we think we have more work than we do.